Porous polymeric particles have been prepared and used for many different purposes. For example, porous particles have been described for use in chromatographic columns, ion exchange and adsorption resins, cosmetic formulations, papers, and paints. The methods for generating pores in polymeric particles are well known in the field of polymer science. However, each particular porous particle often requires unique methods for their manufacture. Some methods of manufacture produce large particles without any ability to control of the pore size while other manufacturing methods control the pore size without controlling the overall particle size.
Marker materials can be included in porous particles so that the particles can be detected for a specific purpose. For example, U.S. Patent Applications 2008/0176157 (Nair et al.) and 2010/0021838 (Putnam et al.) and U.S. Pat. No. 7,754,409 (Nair et al.) describe porous particles and a method for their manufacture, which porous particles are designed to be toner particles for use in electrophotography. Such porous particles typically contain a colorant and can be prepared using a multiple emulsion process in combination with a suspension process (such as “evaporative limited coalescence”, ELC) in a reproducible manner and with a narrow particle size distribution.
Still another important use of polymeric particles is as a means for marking documents, clothing, or labels as a “security” tag, for example for authentication of documents using an electrophotographic process and core-shell toner particles containing an infrared emitting component and a detection step. For example, U.S. Patent Application Publication 2003/0002029 (Dukler et al.) describes a method for labeling documents for authentication using a toner particle containing two or more mixed compounds having a characteristic detectable signal.
U.S. Pat. No. 8,110,628 (Nair et al.) describes porous particles and articles containing same that contain various marker materials within discrete pores for specific means of detection. These porous particles can be prepared using multiple water-in-oil emulsions containing the desired markers and pore stabilizing hydrocolloids to prevent coalescence of the pore forming water-in-oil droplets.
Catalytic nanoparticle encapsulation in microcapsules is described by Parthasarathy et al. in J. Applied Polymer Sci., 62, 875-886 (1996). However, these microcapsules are tubular and do not contain multiple discrete cavities.
Organic catalytically reactive materials, such as enzymes, can be used in compositions for many purposes but there is always a need to protect people and the environment from chemicals such as enzymes that are used in chemical reactions. Another desire is to extend the useful lifetime of organic catalytic materials in certain applications by preventing degradation by adventitious hydrolytic enzymes or digestion by microorganisms. There is also desire for improved handling of organic catalytic materials. There is a further desire to find a means for providing micro-sized materials containing nano-sized organic reactive materials that can also be reused while retaining high reactive capability.